Did Mrs. Clinton suffer (does suffers) from a traumatic brain injury? It sure looks like she did, from Daily Mail (UK):

A prominent New York ophthalmologist believes that a special pair of glasses worn by former former Secretary of State Hillary Clinton are the type used to treat the double vision sometimes caused by severe head trauma.

In an interview with Fox News, Dr. Marc Werner said the glasses had a Fresnel prism.

‘In order to see one object, your eyes need to be pointed in the same direction. If your eyes are misaligned, one way to optically align them is to put a prism … on your glasses,’ he said.